Dental radiographs are made using X-ray examination units including an X-ray cone or tube positioned proximate the patient and aligned to take X-rays of certain teeth. Dental X-ray films developed for intraoral shots generally have a plate like construction and standardized dimensions so that the film can be introduced into the oral cavity.
In one procedure, the film alone is placed within the patient's mouth and held in place proximate the tooth or teeth to be filmed when the patient closes her mouth over the film. It has been determined, however, the proper orientation of the film with respect to the tooth or teeth to be filmed (for example, parallel to the longitudinal axis of the tooth), is required to eliminate distortions, improper focus and the like.
Therefore, film carriers ("bite blocks") are used which have a back plate for mounting the X-ray film and a bite plate orientated at the right angle to the back plate. The X-ray film is held against the back plate, the film carrier is introduced at the proper location within the patient's mouth, and the patient is instructed to bite down on the bite plate. The film carriers have different shapes depending on the area of the mouth to be filmed, e.g., anterior, vertical bite wing, upper left/lower right or upper right/lower left, and bite wing film carriers.
There is still a need, however, to insure proper orientation of the X-ray tube with respect to the X-ray film mounted against the backplate. The procedure for accomplishing this goal is not always straight forward. The following is an excerpt of a filming procedure using a typical prior art film positioning system disclosed in U.S. Pat. No. 4,949,370, Column 9, line 50--Column 10, line 7:
i. Left upper jaw . . . select mounting face 16b with indicating portion 15b positioned upwardly (inclined); select mounting face 16d with indicating portion 15a positioned upwardly (not inclined). PA1 ii. Left lower jaw . . . select mounting face 16d with indicating portion 15b positioned downwardly (inclined); select mounting face 16b with indicating portion 15a positioned downwardly (not inclined). PA1 iii. Right upper jaw . . . select mounting faced 16d with indicating portion 15b positioned upwardly (inclined); select mounting face 16b with indicating portion 15a positioned upwardly (not inclined). PA1 iv. Left lower jaw . . . select mounting face 16b with indicating portion 15b positioned downwardly (inclined); select mounting face 16d with indicating portion 15a positioned downwardly (not inclined). PA1 v. Front upper jaw . . . select mounting face 16b or 16d with indicating portion 15b positioned upwardly (inclined); select mounting face 16b or 16d with indicating portion 15a positioned upwardly (not inclined). PA1 vi. Front lower jaw . . . select mounting face 16b or 16d with indicating portion 15b positioned downwardly (inclined); select mounting face 16b or 16d with indicating portion 15a positioned downwardly (not inclined).
One inventor of the instant invention greatly simplified this difficult to understand prior art procedure by engineering the device depicted in U.S. Pat. No. 5,327,477 incorporated herein by reference. In that patent there are three rod holders each annotated to match a specific film holder.
In the instant invention, the inventors have devised an even simpler system.